As the title says. I'm playing the Japanese version of a game and came across the last two words. I've researched into them and the best I can describe them is that they both mean "to be helpful/useful."
In my notes about vocab I come across in the game, I write that the difference between 手伝う and 力になる is that the latter is used for, and I quote, "slightly bigger situations or wanting to be 'dependable' in some way." However, I'm unable to discern the difference 力になる and 役に立つ.
So, my main question is, what are/are there any fundamental differences between these three words and, if so, what context is each appropriate to use in?